bioRxiv preprint doi: https://doi.org/10.1101/533174; this version posted January 29, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Pharmacological inhibition of GPR4 remediates intestinal inflammation in a mouse colitis model Edward J. Sanderlina, Mona Mariea, Juraj Velcickyc, Pius Loetscherc, Li V. Yanga,b,* aDepartment of Internal Medicine, Brody School of Medicine, East Carolina University, USA bDepartment of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, USA cNovartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland * Corresponding author: Li V. Yang, Ph.D., Department of Internal Medicine, Brody School of Medicine, East Carolina University, 600 Moye Blvd., Greenville, NC 27834, U.S.A. Email: [email protected]; Phone: +1-252-744-3419 bioRxiv preprint doi: https://doi.org/10.1101/533174; this version posted January 29, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Abstract Inflammatory bowel disease (IBD) is characterized by chronic, recurring inflammation of the digestive tract. Current therapeutic approaches are limited and include biologics and steroids such as anti-TNFα monoclonal antibodies and corticosteroids, respectively. Significant adverse drug effects can occur for chronic usage and include increased risk of infection in some patients. GPR4, a pH-sensing G protein-coupled receptor, has recently emerged as a potential therapeutic target for intestinal inflammation. We have assessed the effects of a GPR4 antagonist, 2-(4-((2-Ethyl-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)methyl)phenyl)-5- (piperidin-4-yl)-1,3,4-oxadiazole (GPR4 antagonist 13, also known as NE 52-QQ57) in the dextran sulfate sodium (DSS)-induced acute colitis mouse model. The GPR4 antagonist 13 inhibited intestinal inflammation. The clinical parameters such as body weight loss and fecal score were reduced in the GPR4 antagonist 13 treatment group compared to vehicle control. Macroscopic disease indicators such as colon shortening, splenic expansion, and mesenteric lymph node enlargement were all reduced in severity in the GPR4 antagonist 13 treated mice. Histopathological features of active colitis were alleviated in GPR4 antagonist 13 treatment groups compared to vehicle control. Finally, inflammatory gene expression in the colon tissues and vascular adhesion molecule expression in the intestinal endothelia were attenuated by GPR4 antagonist 13. Our results indicate that GPR4 antagonist 13 provides a protective effect in the DSS-induced acute colitis mouse model, and inhibition of GPR4 can be explored as a novel anti-inflammatory approach. Keywords: GPR4; G protein-coupled receptor; antagonist; colitis; inflammatory bowel disease bioRxiv preprint doi: https://doi.org/10.1101/533174; this version posted January 29, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1. Introduction Inflammatory bowel disease (IBD) is complex and characterized by dysregulated mucosal immune responses. Uncontrolled chronic gastrointestinal inflammation can result in severe complications which include fistulas and stenosis (Hendrickson et al., 2002; Kaser et al., 2010). Furthermore, IBD can have extrainstestinal manifestations such as arthritis and uveitis (Hendrickson et al., 2002). Additionally, IBD can also increase the risk of the development of colon cancer (Mattar et al., 2011). The current therapeutic landscape for IBD is limited and predominately focused on symptomatic management (Neurath, 2017). IBD can take the form of ulcerative colitis (UC) and Crohn’s disease (CrD). One feature noted in IBD is the display of reduced intra-intestinal luminal pH in IBD patients compared to healthy controls (Fallingborg et al., 1993; Nugent et al., 2001). It is also well documented local tissue pH can be reduced during active inflammation, predominately owing to heightened metabolic byproducts from excessive leukocyte infiltration and hypoxia (Justus et al., 2015; Lardner, 2001; Okajima, 2013). These studies collectively suggest the intestinal mucosa and lumen can be acidic in IBD patients. It remains poorly investigated, however, how cellular constituents involved in the mucosal immune response sense altered pH in the intestine and subsequently alter function. G-protein-coupled receptors (GPCRs) are implicated in normal intestinal function as well as in pathological contribution during active IBD. One such family of GPCRs are the proton- sensing GPCRs, which consist of GPR4, GPR65 (TDAG8), and GPR68 (OGR1) (Justus et al., 2013; Justus et al., 2017; Ludwig et al., 2003; Sanderlin et al., 2015). These receptors have been implicated in the modulation of intestinal inflammation (de Valliere et al., 2015; Lassen et al., bioRxiv preprint doi: https://doi.org/10.1101/533174; this version posted January 29, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 2016; Sanderlin et al., 2017; Wang et al., 2018). Studies have shown GPR4 is responsible for acidosis-induced endothelial cell inflammation and can functionally increase leukocyte adhesion with endothelial cells (Chen et al., 2011; Dong et al., 2017; Dong et al., 2013; Tobo et al., 2015). GPR4 genetic deletion in mice reduces intestinal inflammation and mucosal leukocyte infiltration in both inducible and spontaneous colitis mouse models (Sanderlin et al., 2017; Wang et al., 2018). However, the effects of pharmacological modulators of proton- sensing GPCRs in intestinal inflammation have not been investigated. In this study, we have assessed a GPR4 antagonist, 2-(4-((2-Ethyl-5,7- dimethylpyrazolo[1,5-a]pyrimidin-3-yl)methyl)phenyl)-5-(piperidin-4-yl)-1,3,4-oxadiazole (GPR4 antagonist 13, also known as NE 52-QQ57), within the dextran sulfate sodium (DSS)-induced acute colitis mouse model as a potential therapeutic for the remediation of intestinal inflammation. GPR4 antagonist 13 was recently developed by Novartis and shown effective following oral administration (Velcicky et al., 2017). GPR4 antagonist 13 could reduce arthritis inflammation, angiogenesis, and nociception in animal models (Velcicky et al., 2017). Furthermore, oral pharmacokinetics, GPR4 target selectivity, dosage and potency was thoroughly evaluated (Velcicky et al., 2017). Another study evaluated GPR4 antagonist 13 in mouse ventilatory responses and observed no obvious toxicities (Hosford et al., 2018). Our results demonstrated that GPR4 antagonist 13 administration reduced disease severity, histopathological features, inflammatory gene expression, and endothelial-specific adhesion molecule expression within the inflamed intestinal tissue in the DSS-induced colitis mouse model. bioRxiv preprint doi: https://doi.org/10.1101/533174; this version posted January 29, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 2. Materials and methods 2.1. Dextran sulfate sodium (DSS)-induced colitis mouse model and GPR4 antagonist 13 delivery Male and female mice of ages 9-10 weeks in the C57BL/6 background were used for experiments. As previously described, mice were maintained specific pathogen free and housed in an Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC)- accredited facility (Sanderlin et al., 2017). The animal use protocol was approved by the Institutional Animal Care and Use Committee (IACUC) of East Carolina University. Acute experimental colitis was induced by the addition of 3% (w/v) Dextran Sulfate Sodium Salt (DSS) ad libitum into the normal drinking water of mice (36,000–50,000 M.Wt, Lot# Q5229, MP Biomedical, Solon, OH). Mice were provided normal pelleted diet ad libitum during experimentation (ProLab 2000, Purina Mills, St. Louis, MO). Mice were treated for seven days with 3% DSS with replacement of the 3% DSS solution every two days. As previously described, during each day of the experimental course clinical parameters for disease severity were assessed (Sanderlin et al., 2017). Mice were weighed for body weight loss evaluation and feces was assessed for fecal blood and diarrhea using the Hemoccult Single Slides screening test (Beckman Coulter, Brea, CA). For GPR4 antagonist 13 administration, the small molecule was suspended in 0.5% methylcellulose/ 0.5% Tween 80/ 99% water and a dosage of 30mg/kg (b.i.d.) was given to mice as previously described (Velcicky et al., 2017). On day one, mice were orally gavaged with either vehicle or 30mg/kg GPR4 antagonist 13 in the morning followed by addition of 3% DSS into the drinking water and another dose of GPR4 antagonist 13 or vehicle in the afternoon. On days two through six, mice were orally gavaged with vehicle or GPR4 antagonist 13 twice a day (b.i.d.).